packfile: use hashmap_entry in delta_base_cache_entry

Eric Wong · gitster · commit d0a48a0a1d0d · 2019-10-07T10:20:09.000+09:00
This hashmap_entry_init function is intended to take a
hashmap_entry struct pointer, not a hashmap struct pointer.

This was not noticed because hashmap_entry_init takes a "void *"
arg instead of "struct hashmap_entry *", and the hashmap struct
is larger and can be cast into a hashmap_entry struct without
data corruption.

This has the beneficial side effect of reducing the size of
a delta_base_cache_entry from 104 bytes to 72 bytes on 64-bit
systems.

Signed-off-by: Eric Wong &lt;e@80x24.org&gt;
Reviewed-by: Derrick Stolee &lt;stolee@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/packfile.c b/packfile.c
@@ -1361,7 +1361,7 @@ struct delta_base_cache_key {
 };
 
 struct delta_base_cache_entry {
-	struct hashmap hash;
+	struct hashmap_entry ent;
 	struct delta_base_cache_key key;
 	struct list_head lru;
 	void *data;
